<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<input type="text" size="3">+
		<input type="text" size="3">=
		<input type="text" size="3" disabled="disabled">
		
		<script src="js/jquery-3.7.0.min.js" type="text/javascript" charset="utf-8"></script>
		<script type="text/javascript">
			$(":text").eq(1).change(function(){
				var num1 = $("input").eq(0).val()-0;
				var num2 = $("input").eq(1).val()-0;
				$(":disabled").val(num1+num2);
			})
			/*
			$("input").get(1).onchange = function(){
				
			}
			*/
		</script>
	</body>
</html>
